There is a concern about leaving some of these products in a barrel overnight.

Eric Cortina and others use CLR for powder fouling on stainless barrels. I tried it and it does work. He also said he filled a bore and let it soak overnight. I probably would not do that due to the caustic agents. Stainless is good stuff but I don't think I'd push my luck with that. I also would not use it on a CM barrel due to the caustic nature. And it will quickly remove bluing.

Ammonia is another one that really should not be left in a CM barrel for hours on end. Stainless might be ok. This is one of the reasons I went to the non-ammonia copper removers. Wipe, let sit for 30seconds, check barrel for copper, repeat. Usually takes less than 15 min to get a fouled barrel cleaned of copper.

I will have to try Wipeout as it does not seem to contain any caustics or acids. Don't see how it dissolves chemically reacts with copper, but, since it seems to will try it.

FWIW, KG-12 does not turn blue when it dissolves copper. Different reaction. To test the Kroil I'd find a copper fouled barrel and apply it. Watch to see of the copper goes away.